@article{10_4064_cm91_1_7,
     author = {Pawe{\l} Krupski},
     title = {Hyperspaces of universal curves
and $2$-cells are true $F_{\sigma \delta }$-sets},
     journal = {Colloquium Mathematicum},
     pages = {91--98},
     publisher = {mathdoc},
     volume = {91},
     number = {1},
     year = {2002},
     doi = {10.4064/cm91-1-7},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm91-1-7/}
}